<?php
    // +----------------------------------------------------------------------
    // | ThinkPHP [ WE CAN DO IT JUST THINK ]
    // +----------------------------------------------------------------------
    // | Copyright (c) 2006~2017 http://thinkphp.cn All rights reserved.
    // +----------------------------------------------------------------------
    // | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
    // +----------------------------------------------------------------------
    // | Author: liu21st <liu21st@gmail.com>
    // +----------------------------------------------------------------------
    namespace think\model\relation;

    use think\Collection;
    use think\db\Query;
    use think\Exception;
    use think\Loader;
    use think\Model;
    use think\model\Pivot;
    use think\model\Relation;
    use think\Paginator;

    class BelongsToMany extends Relation {
        // 中间表表名
        protected $middle;
        // 中间表模型名称
        protected $pivotName;
        // 中间表模型对象
        protected $pivot;

        /**
         * 构造函数
         * @access public
         * @param Model  $parent     上级模型对象
         * @param string $model      模型名
         * @param string $table      中间表名
         * @param string $foreignKey 关联模型外键
         * @param string $localKey   当前模型关联键
         */
        public function __construct(Model $parent, $model, $table, $foreignKey, $localKey) {
            $this->parent     = $parent;
            $this->model      = $model;
            $this->foreignKey = $foreignKey;
            $this->localKey   = $localKey;
            if (false !== strpos($table, '\\')) {
                $this->pivotName = $table;
                $this->middle    = basename(str_replace('\\', '/', $table));
            } else {
                $this->middle = $table;
            }
            $this->query = (new $model)->db();
            $this->pivot = $this->newPivot();
        }

        /**
         * 实例化中间表模型
         * @param $data
         * @return mixed
         */
        protected function newPivot($data = []) {
            $pivot = $this->pivotName ?: '\\think\\model\\Pivot';
            return new $pivot($this->parent, $data, $this->middle);
        }

        /**
         * 设置中间表模型
         * @param $pivot
         * @return $this
         */
        public function pivot($pivot) {
            $this->pivotName = $pivot;
            return $this;
        }

        /**
         * 延迟获取关联数据
         * @param string   $subRelation 子关联名
         * @param \Closure $closure     闭包查询条件
         * @return false|\PDOStatement|string|\think\Collection
         */
        public function getRelation($subRelation = '', $closure = null) {
            if ($closure) {
                call_user_func_array($closure, [& $this->query]);
            }
            $result = $this->buildQuery()->relation($subRelation)->select();
            $this->hydratePivot($result);
            return $result;
        }

        /**
         * 创建关联查询Query对象
         * @return Query
         */
        protected function buildQuery() {
            $foreignKey = $this->foreignKey;
            $localKey   = $this->localKey;
            $middle     = $this->middle;
            // 关联查询
            $pk                              = $this->parent->getPk();
            $condition['pivot.' . $localKey] = $this->parent->$pk;
            return $this->belongsToManyQuery($foreignKey, $localKey, $condition);
        }

        /**
         * BELONGS TO MANY 关联查询
         * @access public
         * @param string $foreignKey 关联模型关联键
         * @param string $localKey   当前模型关联键
         * @param array  $condition  关联查询条件
         * @return Query
         */
        protected function belongsToManyQuery($foreignKey, $localKey, $condition = []) {
            // 关联查询封装
            $tableName = $this->query->getTable();
            $table     = $this->pivot->getTable();
            $fields    = $this->getQueryFields($tableName);
            $query     = $this->query->field($fields)->field(true, false, $table, 'pivot', 'pivot__');
            if (empty($this->baseQuery)) {
                $relationFk = $this->query->getPk();
                $query->join($table . ' pivot', 'pivot.' . $foreignKey . '=' . $tableName . '.' . $relationFk)->where($condition);
            }
            return $query;
        }

        /**
         * 合成中间表模型
         * @param array|Collection|Paginator $models
         */
        protected function hydratePivot($models) {
            foreach ($models as $model) {
                $pivot = [];
                foreach ($model->getData() as $key => $val) {
                    if (strpos($key, '__')) {
                        list($name, $attr) = explode('__', $key, 2);
                        if ('pivot' == $name) {
                            $pivot[$attr] = $val;
                            unset($model->$key);
                        }
                    }
                }
                $model->pivot = $this->newPivot($pivot);
            }
        }

        /**
         * 重载paginate方法
         * @param null  $listRows
         * @param bool  $simple
         * @param array $config
         * @return Paginator
         */
        public function paginate($listRows = null, $simple = false, $config = []) {
            $result = $this->buildQuery()->paginate($listRows, $simple, $config);
            $this->hydratePivot($result);
            return $result;
        }

        /**
         * 查找多条记录 如果不存在则抛出异常
         * @access public
         * @param array|string|Query|\Closure $data
         * @return array|\PDOStatement|string|Model
         */
        public function selectOrFail($data = null) {
            return $this->failException(true)->select($data);
        }

        /**
         * 重载select方法
         * @param null $data
         * @return false|\PDOStatement|string|Collection
         */
        public function select($data = null) {
            $result = $this->buildQuery()->select($data);
            $this->hydratePivot($result);
            return $result;
        }

        /**
         * 查找单条记录 如果不存在则抛出异常
         * @access public
         * @param array|string|Query|\Closure $data
         * @return array|\PDOStatement|string|Model
         */
        public function findOrFail($data = null) {
            return $this->failException(true)->find($data);
        }

        /**
         * 重载find方法
         * @param null $data
         * @return array|false|\PDOStatement|string|Model
         */
        public function find($data = null) {
            $result = $this->buildQuery()->find($data);
            $this->hydratePivot([$result]);
            return $result;
        }

        /**
         * 根据关联条件查询当前模型
         * @access public
         * @param string  $operator 比较操作符
         * @param integer $count    个数
         * @param string  $id       关联表的统计字段
         * @param string  $joinType JOIN类型
         * @return Query
         */
        public function has($operator = '>=', $count = 1, $id = '*', $joinType = 'INNER') {
            return $this->parent;
        }

        /**
         * 根据关联条件查询当前模型
         * @access public
         * @param mixed $where 查询条件（数组或者闭包）
         * @return Query
         * @throws Exception
         */
        public function hasWhere($where = []) {
            throw new Exception('relation not support: hasWhere');
        }

        /**
         * 设置中间表的查询条件
         * @param      $field
         * @param null $op
         * @param null $condition
         * @return $this
         */
        public function wherePivot($field, $op = null, $condition = null) {
            $field = 'pivot.' . $field;
            $this->query->where($field, $op, $condition);
            return $this;
        }

        /**
         * 预载入关联查询（数据集）
         * @access public
         * @param array    $resultSet   数据集
         * @param string   $relation    当前关联名
         * @param string   $subRelation 子关联名
         * @param \Closure $closure     闭包
         * @return void
         */
        public function eagerlyResultSet(&$resultSet, $relation, $subRelation, $closure) {
            $localKey   = $this->localKey;
            $foreignKey = $this->foreignKey;
            $pk         = $resultSet[0]->getPk();
            $range      = [];
            foreach ($resultSet as $result) {
                // 获取关联外键列表
                if (isset($result->$pk)) {
                    $range[] = $result->$pk;
                }
            }
            if (!empty($range)) {
                // 查询关联数据
                $data = $this->eagerlyManyToMany([
                                                     'pivot.' . $localKey => [
                                                         'in',
                                                         $range,
                                                     ],
                                                 ], $relation, $subRelation
                );
                // 关联属性名
                $attr = Loader::parseName($relation);
                // 关联数据封装
                foreach ($resultSet as $result) {
                    if (!isset($data[$result->$pk])) {
                        $data[$result->$pk] = [];
                    }
                    $result->setRelation($attr, $this->resultSetBuild($data[$result->$pk]));
                }
            }
        }

        /**
         * 多对多 关联模型预查询
         * @access public
         * @param array  $where       关联预查询条件
         * @param string $relation    关联名
         * @param string $subRelation 子关联
         * @return array
         */
        protected function eagerlyManyToMany($where, $relation, $subRelation = '') {
            // 预载入关联查询 支持嵌套预载入
            $list = $this->belongsToManyQuery($this->foreignKey, $this->localKey, $where)->with($subRelation)->select();
            // 组装模型数据
            $data = [];
            foreach ($list as $set) {
                $pivot = [];
                foreach ($set->getData() as $key => $val) {
                    if (strpos($key, '__')) {
                        list($name, $attr) = explode('__', $key, 2);
                        if ('pivot' == $name) {
                            $pivot[$attr] = $val;
                            unset($set->$key);
                        }
                    }
                }
                $set->pivot                      = $this->newPivot($pivot);
                $data[$pivot[$this->localKey]][] = $set;
            }
            return $data;
        }

        /**
         * 预载入关联查询（单个数据）
         * @access public
         * @param Model    $result      数据对象
         * @param string   $relation    当前关联名
         * @param string   $subRelation 子关联名
         * @param \Closure $closure     闭包
         * @return void
         */
        public function eagerlyResult(&$result, $relation, $subRelation, $closure) {
            $pk = $result->getPk();
            if (isset($result->$pk)) {
                $pk = $result->$pk;
                // 查询管理数据
                $data = $this->eagerlyManyToMany(['pivot.' . $this->localKey => $pk], $relation, $subRelation);
                // 关联数据封装
                if (!isset($data[$pk])) {
                    $data[$pk] = [];
                }
                $result->setRelation(Loader::parseName($relation), $this->resultSetBuild($data[$pk]));
            }
        }

        /**
         * 关联统计
         * @access public
         * @param Model    $result  数据对象
         * @param \Closure $closure 闭包
         * @return integer
         */
        public function relationCount($result, $closure) {
            $pk    = $result->getPk();
            $count = 0;
            if (isset($result->$pk)) {
                $pk    = $result->$pk;
                $count = $this->belongsToManyQuery($this->foreignKey, $this->localKey, ['pivot.' . $this->localKey => $pk])->count();
            }
            return $count;
        }

        /**
         * 获取关联统计子查询
         * @access public
         * @param \Closure $closure 闭包
         * @return string
         */
        public function getRelationCountQuery($closure) {
            return $this->belongsToManyQuery($this->foreignKey, $this->localKey, [
                                                                  'pivot.' . $this->localKey => [
                                                                      'exp',
                                                                      '=' . $this->parent->getTable() . '.' . $this->parent->getPk(),
                                                                  ],
                                                              ]
            )->fetchSql()->count();
        }

        /**
         * 保存（新增）当前关联数据对象
         * @access public
         * @param mixed $data  数据 可以使用数组 关联模型对象 和 关联对象的主键
         * @param array $pivot 中间表额外数据
         * @return integer
         */
        public function save($data, array $pivot = []) {
            // 保存关联表/中间表数据
            return $this->attach($data, $pivot);
        }

        /**
         * 附加关联的一个中间表数据
         * @access public
         * @param mixed $data  数据 可以使用数组、关联模型对象 或者 关联对象的主键
         * @param array $pivot 中间表额外数据
         * @return array|Pivot
         * @throws Exception
         */
        public function attach($data, $pivot = []) {
            if (is_array($data)) {
                if (key($data) === 0) {
                    $id = $data;
                } else {
                    // 保存关联表数据
                    $model = new $this->model;
                    $model->save($data);
                    $id = $model->getLastInsID();
                }
            } elseif (is_numeric($data) || is_string($data)) {
                // 根据关联表主键直接写入中间表
                $id = $data;
            } elseif ($data instanceof Model) {
                // 根据关联表主键直接写入中间表
                $relationFk = $data->getPk();
                $id         = $data->$relationFk;
            }
            if ($id) {
                // 保存中间表数据
                $pk                     = $this->parent->getPk();
                $pivot[$this->localKey] = $this->parent->$pk;
                $ids                    = (array)$id;
                foreach ($ids as $id) {
                    $pivot[$this->foreignKey] = $id;
                    $this->pivot->insert($pivot, true);
                    $result[] = $this->newPivot($pivot);
                }
                if (count($result) == 1) {
                    // 返回中间表模型对象
                    $result = $result[0];
                }
                return $result;
            } else {
                throw new Exception('miss relation data');
            }
        }

        /**
         * 批量保存当前关联数据对象
         * @access public
         * @param array $dataSet   数据集
         * @param array $pivot     中间表额外数据
         * @param bool  $samePivot 额外数据是否相同
         * @return integer
         */
        public function saveAll(array $dataSet, array $pivot = [], $samePivot = false) {
            $result = false;
            foreach ($dataSet as $key => $data) {
                if (!$samePivot) {
                    $pivotData = isset($pivot[$key]) ? $pivot[$key] : [];
                } else {
                    $pivotData = $pivot;
                }
                $result = $this->attach($data, $pivotData);
            }
            return $result;
        }

        /**
         * 数据同步
         * @param array $ids
         * @param bool  $detaching
         * @return array
         */
        public function sync($ids, $detaching = true) {
            $changes = [
                'attached' => [],
                'detached' => [],
                'updated'  => [],
            ];
            $pk      = $this->parent->getPk();
            $current = $this->pivot->where($this->localKey, $this->parent->$pk)->column($this->foreignKey);
            $records = [];
            foreach ($ids as $key => $value) {
                if (!is_array($value)) {
                    $records[$value] = [];
                } else {
                    $records[$key] = $value;
                }
            }
            $detach = array_diff($current, array_keys($records));
            if ($detaching && count($detach) > 0) {
                $this->detach($detach);
                $changes['detached'] = $detach;
            }
            foreach ($records as $id => $attributes) {
                if (!in_array($id, $current)) {
                    $this->attach($id, $attributes);
                    $changes['attached'][] = $id;
                } elseif (count($attributes) > 0 && $this->attach($id, $attributes)) {
                    $changes['updated'][] = $id;
                }
            }
            return $changes;
        }

        /**
         * 解除关联的一个中间表数据
         * @access public
         * @param integer|array $data        数据 可以使用关联对象的主键
         * @param bool          $relationDel 是否同时删除关联表数据
         * @return integer
         */
        public function detach($data = null, $relationDel = false) {
            if (is_array($data)) {
                $id = $data;
            } elseif (is_numeric($data) || is_string($data)) {
                // 根据关联表主键直接写入中间表
                $id = $data;
            } elseif ($data instanceof Model) {
                // 根据关联表主键直接写入中间表
                $relationFk = $data->getPk();
                $id         = $data->$relationFk;
            }
            // 删除中间表数据
            $pk                     = $this->parent->getPk();
            $pivot[$this->localKey] = $this->parent->$pk;
            if (isset($id)) {
                $pivot[$this->foreignKey] = is_array($id) ? [
                    'in',
                    $id
                ] : $id;
            }
            $this->pivot->where($pivot)->delete();
            // 删除关联表数据
            if (isset($id) && $relationDel) {
                $model = $this->model;
                $model::destroy($id);
            }
        }

        /**
         * 执行基础查询（进执行一次）
         * @access protected
         * @return void
         */
        protected function baseQuery() {
            if (empty($this->baseQuery) && $this->parent->getData()) {
                $pk    = $this->parent->getPk();
                $table = $this->pivot->getTable();
                $this->query->join($table . ' pivot', 'pivot.' . $this->foreignKey . '=' . $this->query->getTable() . '.' . $this->query->getPk())
                            ->where('pivot.' . $this->localKey, $this->parent->$pk);
                $this->baseQuery = true;
            }
        }
    }
